Re: Apple II NTSC emulation

[vladitx <vladitx@nucleusys.com>]

On Aug 6, 1:50 pm, Alex Freed <alex_n...@mirrow.com> wrote:

> We only have 2 bits per color but with a lot of vertical resolution
> lines be can emulate another bit by dithering. But I guess it's not
> worth the trouble. GS look is good enough for me :)

Alex, check these pictures - it's a quick FPGA estimation I did:
http://www.softjunk.org/sw/apple2/ra2/files/screenshot/ntsc/bpp/

The name describes total DAC bits per pixel, so these translate to 2,
3, 4 and 8 bits per component. Alas, 2 bits is insufficient, but 3 is
really the sweetspot (I even guessed on this one). Ignoring the
reduced luminosity in the 9bpp, 12bpp and 24bpp examples due to very
crude quick'n'dirty bit shifting, they are practically looking the
same to me. With careful rounding and color selection it'll look just
as well in 9 bpp.

All the data fits in 4 BRAMs in 2Kx9 mode for 9bpp mode. The rest
boils down to two shift registers and a mux. :-)